Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753594AbaLOOfA (ORCPT ); Mon, 15 Dec 2014 09:35:00 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:38930 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753024AbaLOO3G (ORCPT ); Mon, 15 Dec 2014 09:29:06 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Anton Vorontsov , Andrew Morton , Linus Torvalds , Luis Henriques Subject: [PATCH 3.16.y-ckt 142/168] mm/vmpressure.c: fix race in vmpressure_work_fn() Date: Mon, 15 Dec 2014 14:26:36 +0000 Message-Id: <1418653622-21105-143-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 2.1.3 In-Reply-To: <1418653622-21105-1-git-send-email-luis.henriques@canonical.com> References: <1418653622-21105-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.7-ckt3 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Andrew Morton commit 91b57191cfd152c02ded0745250167d0263084f8 upstream. In some android devices, there will be a "divide by zero" exception. vmpr->scanned could be zero before spin_lock(&vmpr->sr_lock). Addresses https://bugzilla.kernel.org/show_bug.cgi?id=88051 [akpm@linux-foundation.org: neaten] Reported-by: ji_ang Cc: Anton Vorontsov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Luis Henriques --- mm/vmpressure.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/mm/vmpressure.c b/mm/vmpressure.c index d4042e75f7c7..c5afd573d7da 100644 --- a/mm/vmpressure.c +++ b/mm/vmpressure.c @@ -165,6 +165,7 @@ static void vmpressure_work_fn(struct work_struct *work) unsigned long scanned; unsigned long reclaimed; + spin_lock(&vmpr->sr_lock); /* * Several contexts might be calling vmpressure(), so it is * possible that the work was rescheduled again before the old @@ -173,11 +174,12 @@ static void vmpressure_work_fn(struct work_struct *work) * here. No need for any locks here since we don't care if * vmpr->reclaimed is in sync. */ - if (!vmpr->scanned) + scanned = vmpr->scanned; + if (!scanned) { + spin_unlock(&vmpr->sr_lock); return; + } - spin_lock(&vmpr->sr_lock); - scanned = vmpr->scanned; reclaimed = vmpr->reclaimed; vmpr->scanned = 0; vmpr->reclaimed = 0; -- 2.1.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/